The present invention relates to a dispenser for media, particularly for discharge of fluids. Such dispensers are used for discharging fluids containing at least one pharmaceutical substance in a clearly defined dose, particularly by atomized spraying.
The atomized discharge of such fluids can take place in intranasal manner. Preferably a precisely dosed, equal medium quantity is discharged into each of the two nostrils. Pharmaceutical substances or substance combinations, which can be discharged in this way, can e.g. be opiates, but in general terms reference is also made to other active substances, particularly anticephalalgics and analgesics. They can be used in medicaments for the treatment of chronic illnesses and/or requiring a continuous application (e.g. diabetes, cardiovascular diseases, etc.). The suitability of an active substance for such a discharge is dependent on the fact that the active substance can be absorbed by the mucosa, particularly the nasal mucosa. The introduction of the medium though the nasal mucosa is particularly advantageous, because it ensures a rapid absorption and rapid introduction into the body and particularly the cerebral region of the body.
Such dispensers have a storage container storing the corresponding medium. The storage container is linked by a media path with a dispenser discharge opening e.g. a spray nozzle. There is also an operable delivery device in the media path which delivers the medium from the storage container to the discharge opening. A delivery process takes place when an operating or actuating means is operated. The delivery device is generally constituted by a piston pump, so that the discharge medium quantity substantially corresponds to the volume of the working chamber of the piston pump. The piston pump are more particularly plunger pumps.
This quantity is not always reliable in establishing the quantity of the medium actually discharged. Firstly residual air quantities can be present in the pump piston, which is particularly the case after prolonged storage periods and prior to the first use of the dispenser, when priming of the dispenser is necessary. Priming is done by performing several discharge strokes until the flow path is completely filled with medium. It can also arise that on operating the dispenser no complete operating stroke is performed. It is known that often pumps are designed to force the user during each dispenser operation to perform a complete operating stroke and therefore also a complete discharge stroke of the delivery device. This is however, not always reliable.